Ventilation member

ABSTRACT

A ventilation member ( 100 ) of the invention includes a tubular part ( 11 ), a gas permeable filter ( 19 ), and a cover part ( 31 ). In an attached state where the tubular part ( 11 ) is fit into the cover part ( 31 ), gaps functioning as gas passages (AR 2  and AR 3 ) are formed between a bottom portion ( 35 ) of the cover part ( 31 ) and the gas permeable filter ( 19 ) and between a side wall portion ( 39 ) of the cover part ( 31 ) and a body portion ( 17 ) of the tubular part ( 11 ). The opening area (S 2 ) of a filter-end opening ( 15 ) with respect to an in-plane direction (WL) perpendicular to the thickness direction of the gas permeable filter ( 19 ) is larger than the opening area (S 1 ) of a connection-end opening ( 13 ) with respect to the in-plane direction (WL).

TECHNICAL FIELD

The present invention relates to a ventilation member that makes use ofa gas permeable filter having gas permeability and waterproofness.

BACKGROUND ART

As described, for example, in JP10-085536A and JP2001-143524A,ventilation members used for automobile components (lamps, motors,sensors, switches, ECUs, and so forth) make use of a gas permeablefilter (gas permeable membrane) having gas permeability, dustproofness,and waterproofness. Adaptation of such ventilation members to electricaldevices, such as mobile communication devices, cameras, electricshavers, and electric toothbrushes, now is being discussed.

The ventilation members as described above play a role of eliminating apressure difference between the interior and the exterior of the device,propagating sounds, or discharging a gas generated inside the devicewhile preventing the entry of dust or water into the interior of thedevice. For instance, fogging possibly occurs on a headlight of anautomobile with a change in temperature, and ventilation members areadopted with the aim of preventing or eliminating the occurrence of suchfogging.

Incidentally, if we assume that the dustproof and waterproofcapabilities are the same, then ventilation members are more efficientif they require a shorter time to eliminate a pressure differencebetween the interior and the exterior of the device or a shorter time todischarge a gas generated inside the device. These times can beshortened by increasing a gas permeation quantity per unit time of theventilation members.

Increasing a gas permeation quantity of the ventilation members,however, is not readily achieved. The bottleneck in a gas permeationquantity is a gas permeable filter that has large gas permeationresistance, but the gas permeable filter has been improved to the pointthat further improvement is difficult.

As the ventilation members per se increase in size, the gas permeationquantity naturally increases in proportion. Size changing of theventilation members, however, is not readily adopted, because itinvolves a design change at the other end (at the device end).

Further, in recent years, there has been a need for ventilation membersthat excel more in durability against foreign matter, such as waterdroplets and dust. For example, as ventilation members to be used forlamps or the housings of ECUs in an automobile, there is a need forventilation members not only capable of withstanding car washing, inparticular, high-pressure car washing, but also capable of completelypreventing the entry of water into the interior of the housings.

DISCLOSURE OF THE INVENTION

In view of the foregoing, the invention has an object to provide aventilation member that has a larger gas permeation quantity per unittime.

The invention has another object to provide a ventilation member thatexcels more in durability against foreign matter, such as water dropletsand dust.

More specifically, an aspect of the invention provides a ventilationmember that includes a tubular part, in an interior of which a gaspassage for an object that needs ventilation is formed, a gas permeablefilter disposed at one of openings of the tubular part, and a coverpart, inside of which the tubular part is fit. The tubular part includesa connection-end opening, which is an opening on a side on which theobject is to be connected, a filter-end opening, which is an openingclosed by the gas permeable filter, and a body portion positionedbetween the connection-end opening and the filter-end opening. The coverpart includes a bottom portion that faces the gas permeable filter in anattached state where the tubular part is fit inside from a side of thegas permeable filter and a side wall portion that extends from thebottom portion so as to surround the filter-end opening and the bodyportion from outside. Gaps functioning as gas passages that communicatewith an exterior are formed in the attached state between the bottomportion of the cover part and the gas permeable filter and between theside wall portion of the cover part and the body portion of the tubularpart. An opening area of the filter-end opening with respect to anin-plane direction perpendicular to a thickness direction of the gaspermeable filter is larger than an opening area of the connection-endopening with respect to the in-plane direction.

As has been described, almost all the objects (for example, headlightsand ECUs in an automobile) to which is applied the ventilation member ofthe invention do not allow for a design change only for the ventilationmember. It is therefore normal that a change in dimension and so forthis not allowed at the connection-end opening of the ventilation member.The ventilation member, however, allows for improvement on the side onwhich the gas permeable filter is attached. In other words, theventilation member of the invention is configured in such a manner that,of the openings of the tubular part at the both ends, the opening areaof the filter-end opening, which is the opening on the side on which thegas permeable filter is attached, is intentionally enlarged. Whenconfigured in this manner, it is possible to enlarge the area of the gaspermeable filter that contributes to ventilation without the need tochange the dimension of the connection-end opening. When the area of thegas permeable filter is enlarged, a gas permeation quantity per unittime can be increased in proportion to the enlarged quantity.

In the ventilation member of the invention, it is possible to make aninner wall of the body portion of the tubular part to have a steppedshape or a tapered shape, so that a difference of opening areas isprovided between the connection-end opening and the filter-end openingaccording to the stepped shape or the tapered shape. When configured inthis manner, it is possible to adopt a gas permeable filter having alarge area without the need to increase the dimension of the cover part.

The cover part may include plural spacers that support the tubular partalong the filter-end opening in the attached state where the tubularpart is fit inside the cover part. The plural spacers prevent the bottomportion of the cover part from contacting closely with the gas permeablefilter entirely, so that one of the gaps formed between the bottomportion of the cover part and the gas permeable filter is secured. Whenconfigured in this manner, not only is it possible to protect the gaspermeable filter from dust, water droplets, and a physical shock in areliable manner with the cover part, but it is also possible to form agap that servers as a gas passage between the cover part and the gaspermeable filter. In addition, by providing the spacers that support thetubular part in a distributed manner, it is possible to utilize spacesbetween the respective spacers that are adjacent to each other as gaspassages.

In a more preferable configuration, the body portion of the tubular partmay include an inner body portion and an outer body portion thatsurrounds the inner body portion. Herein, assuming that the thicknessdirection of the gas permeable filter is an axis line direction, a sidein the axis line direction on which the filter-end opening is located isa front side, and a side on which the connection-end opening is locatedis a rear side, then by configuring in such a manner that a front endportion of the inner body portion is retracted to a position in the rearof a front end portion of the outer body portion, it is possible to formthe front end portion of the outer body portion as a thin filter-endopening to which the gas permeable filter is attached. Further, couplingportions formed integrally with the inner body portion and the outerbody portion may be provided between these portions at plural points ina circumferential direction. Accordingly, gaps that open frontward inthe axis line direction and communicate with the space inside the tubeof the tubular part are defined between the respective coupling portionsthat are adjacent to each other. When configured in this manner, it ispossible to form gaps between the inner body portion and the outer bodyportion while producing a change in opening area. Because thisconfiguration in turn can shorten the molding time of the tubular part(to be more concrete, the cooling time), the cost saving derived fromthe enhanced productivity can be expected.

It is also possible to have a structure in which the inner body portionand the outer body portion are connected to each other directly along anentire circumference on the rear side in the axis line direction. Whenconfigured in this manner, it is possible to make the connection-endopening sufficiently thick, and the ventilation member can be attachedto the device that needs ventilation in a reliable manner.

At least one of the cover part and the tubular part may include fixingpieces positioned at plural points in a circumferential directionbetween the tubular part and the side wall portion of the cover part inthe attached state. Also, gaps functioning as gas passages thatcommunicate with the exterior can be formed between the respectivefixing pieces that are adjacent to each other, and relative positions ofthe cover part and the tubular part can be determined through elasticdeformation of at least one of the tubular part and the fixing pieces.According to the fixing pieces as described above, not only can thecover part and the tubular part be fixed relatively with respect to eachother with ease, but also gas passages can be formed naturally betweenthe cover part and the tubular part.

To be more concrete, a material of one of the cover part and the tubularpart is elastomer and a material of the other is resin or metal that hasno rubber elasticity. More preferably, the tubular part is made ofelastomer and the cover part is made of hard resin. Further, fixingpieces, which are in contact with the tubular part in the attached statewhere the tubular part is fit in the cover part, are disposed at theside wall portion of the cover part at plural points in thecircumferential direction. When configured in this manner, the tubularpart is placed under an external force from the fixing pieces in theattached state and undergoes elastic deformation. It is thereforepossible to fix the tubular part and the cover part to each other by anelastic restoring force of the tubular part.

Another aspect of the invention provides a ventilation member thatincludes a tubular part, in an interior of which a gas passage for anobject that needs ventilation is formed, a gas permeable filter attachedto the tubular part, and a cover part that defines a gap between itselfand the gas permeable filter in an attached state where the tubular partis fit inside from a side of the gas permeable filter. The gas passageformed in the interior of the tubular part includes a first gas passagethat is to communicate directly with an interior space of the object anda second gas passage isolated from the first gas passage. The gaspermeable filter is attached to the tubular part so as to close at leastan opening on the basis of the first gas passage. A gas thus is allowedto circulate between the first gas passage and the second gas passagevia the gap and the gas permeable filter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional perspective view of a ventilation member of theinvention.

FIG. 2 is a perspective view of the ventilation member of FIG. 1.

FIG. 3 is a cross section showing a state where the ventilation memberof FIG. 1 and FIG. 2 is attached to the housing of a device that needsventilation.

FIG. 4 is a cross section showing a modification of a tubular part.

FIG. 5 is a perspective view of the tubular part when viewed from afilter end opening.

FIG. 6 is a sectional perspective view of the tubular part when viewedin a cross section cut at a plane different from the plane of the crosssection of FIG. 1.

FIG. 7 is a perspective view of a cover part when viewed from a sidefrom which the tubular part is fit therein.

FIG. 8 is a perspective view of the cover part when viewed from the sideopposite to the side of FIG. 7.

FIG. 9 is a sectional perspective view of a ventilation member of asecond embodiment.

FIG. 10 is a perspective view of the ventilation member of FIG. 9.

FIG. 11 is a perspective view of a tubular part when viewed from afilter-end opening.

FIG. 12 is a perspective view of the tubular part when viewed from aconnection-end opening.

FIG. 13 is a perspective view of a cover part when viewed from a sidefrom which the tubular part is fit therein.

FIG. 14 is a perspective view of the cover part when viewed from theside opposite to the side of FIG. 13.

FIG. 15 is an exploded perspective view of a ventilation member of athird embodiment.

FIG. 16 is a longitudinal cross section of the ventilation member shownin FIG. 15.

FIG. 17 is a longitudinal cross section showing a modification of theventilation member of FIG. 15 and FIG. 16.

FIG. 18 is a perspective view of another suitable tubular part.

FIG. 19 is a perspective view of still another suitable tubular part.

FIG. 20 is a perspective view of still another suitable tubular part.

FIG. 21 is a perspective view of still another suitable tubular part.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

FIG. 1 is a sectional perspective view of a ventilation member of theinvention. FIG. 2 is a perspective view of the ventilation member ofFIG. 1. FIG. 3 is a cross section showing a state where the ventilationmember of FIG. 1 and FIG. 2 is attached to the housing of a device thatneeds ventilation. As is shown in FIG. 3, by attaching a ventilationmember 100 to a nozzle-like filter-attached portion 53 provided to ahousing 51 of the device, it is possible to ventilate the interior ofthe housing 51 while preventing the entry of foreign matter, such aswater droplets. In addition, it is possible to maintain the internalpressure of the housing 51 equal to the external pressure.

As shown in FIG. 1, FIG. 2, and FIG. 3, the ventilation member 100includes a tubular part 11, a gas permeable filter 19, and a cover part31. The gas permeable filter 19, however, is omitted in FIG. 1. Thetubular part 11 is of an almost circular cylindrical shape and forms agas passage AR₁ that directly communicates with the housing 51 of thedevice by making use of a space inside the tube. The gas permeablefilter 19 is attached to an opening 15, which is one of the openings ofthe tubular part 11. The cover part 31 is a part into which the tubularpart 11 attached with the gas permeable filter 19 is fit from the sideof the gas permeable filter 19. As shown in FIG. 1 and FIG. 3, of theopenings of the tubular part 11 at the both ends, the opening area S2 ofthe filter-end opening 15, which is an opening closed by the gaspermeable filter 19, is larger than the opening area S1 of theconnection-end opening 13, which is an opening to which thefilter-attached portion 53 of the housing 51 is to be connected. Whenconfigured in this manner, a gas permeation quantity per unit time canbe increased by enlarging the effective area of the gas permeable filter19 to the extent possible.

The term, “the effective area of the gas permeable filter”, referred toherein means the area of a portion of the gas permeable filter 19 thatactually contributes to ventilation between the interior and theexterior of the tubular part 11. In addition, assuming that an in-planedirection WL is a direction perpendicular to the thickness direction ofthe gas permeable filter 19, then the opening area of the tubular part11 is expressed as the opening area with respect to the in-planedirection WL. As can be understood from FIG. 1 and the other relateddrawings, the thickness direction of the gas permeable filter 19coincides with a direction parallel to the center axis line O of thetubular part 11. The direction parallel to the center axis line O alsois referred to as the axis line direction. In addition, the side onwhich the filter-end opening 15 is located with respect to the directionparallel to the center axis line O (the lower side in FIG. 3) isreferred to as the front side and the side on which the connection-endopening 13 (the upper side in FIG. 3) is located is referred to as therear side.

Hereinafter, reference will be made to the structure of the ventilationmember 100 in a state where respective parts are assembled with eachother by describing these parts individually in detail.

As shown in FIG. 1 and FIG. 3, the tubular part 11 is formed of theconnection-end opening 13, which is an opening to which the device thatneeds ventilation is to be connected, the filter-end opening 15, whichis an opening to which the gas permeable filter 19 is attached, and abody portion 17 that connects the connection-end opening 13 and thefilter-end opening 15. The interior of the body portion 17 defines athrough-hole that penetrates through from the connection-end opening 13to the filter-end opening 15, and this through-hole forms the gaspassage AR₁. A taper TP is provided to the inner peripheral portion ofthe connection-end opening 13 for the nozzle-like filter-attachedportion 53 to be inserted with ease. An opening diameter about thecenter axis line O of the filter-end opening 15 is larger than that ofthe connection-end opening 13 and a thickness in the radius directionthereof is smaller than that of the connection-end opening portion 13.

The term, “the opening diameter of the connection-end opening 13”,referred to herein means the opening diameter of the inner peripheraledge of the taper TP, that is, at the position at which the contactbetween the filter-attached portion 53 and the tubular part 11 begins.This is because the taper TP is provided by taking into account the easeof attachment for the nozzle-like filter-attached portion 53, and theopening diameter of the connection-end opening 13 should be consideredas the position at which a contribution is actually made to theconnection to the filter-attached portion 53.

As shown in FIG. 5 and FIG. 6, the body portion 17 of the tubular part11 is formed of an inner body portion 171 and an outer body portion 173that surrounds the inner body portion 171. The inner body portion 171and the outer body portion 173 are disposed concentrically about thecenter axis line O used in common. It should be noted, however, that theouter body portion 173 is of a shape that slightly extends frontwardmore than the inner body portion 171. In short, the front end portion ofthe outer body portion 173 forms the filter-end opening 15. Bysatisfying the positional relationship as above, the inner wall of thebody portion 17 of the tubular part 11 consequently has a stepped shape.The body portion 17 having the stepped shape produces a step-wise changein opening area in the in-plane direction WL at a specific position withrespect to the direction parallel to the center axis line O. To be morespecific, it is possible to produce a difference of opening areas,ΔS(=S2−S1), between the connection-end opening 13 and the filter-endopening 15 according to the stepped shape of the body portion 17.

In addition, the tubular part 11 includes plural coupling portions 43that couple the inner body portion 171 and the outer body portion 173.The coupling portions 43 are parts that are positioned between the innerbody portion 171 and the outer body portion 173 and formed integrallywith these portions. In this embodiment, the coupling portions 43 areprovided at plural points in the circumferential direction atequiangular intervals. Accordingly, gaps SH are formed between therespective coupling portions 43 and the adjacent coupling portions 43.Each gap SH opens frontward and communicates with the gas passage AR₁ inthe interior of the tubular part 11. Meanwhile, the inner body portion171 and the outer body portion 173 are connected to each other entirelyin the circumferential direction on the rear side. The opening diameterof the connection-end opening 13 corresponds to the minor diameter ofthe inner body portion 171.

The tubular part 11 as described above can be manufactured by moldingresin using a known injection molding process. As shown in FIG. 5 andFIG. 6, by providing the gaps SH between the inner body portion 171 andthe outer body portion 173, it is possible to shorten the cooling timemarkedly during the injection molding. According to the knowledge of theinventors, there is a two-fold difference in cooling time between a casewhere no gaps SH are provided and this embodiment. In short, whenconfigured as in this embodiment, it is expected to achieve the costsaving effect derived from the enhanced productivity.

In this embodiment, thermoplastic elastomer is adopted as a material ofthe tubular part 11. Examples of the thermoplastic elastomer that can beused as the material of the tubular part 11 include but not limited tothermoplastic elastomers based on polystyrene, polyolefin, polyvinylchloride, polyester, polyurethane, polyamide, and fluoropolymer. All ofthese thermoplastic elastomers are suitable owing to their excellentheat resistance, weathering resistance, and chemical resistance.

It is preferable for the thermoplastic elastomer forming the tubularpart 11 to have a compression set of 70% or below (preferably, 50% orbelow) when allowed to stand under the condition of 70° C. for 22 hours(according to JIS K6301) and a hardness of 100 or below (preferably, 80or below) when measured by an A-type spring hardness tester. When thecompression set is too high, oscillations or a temperature changereadily gives rise to a clearance between the filter-attached portion 53of the device (see FIG. 3) and the tubular part 11. Also, when thehardness is too high, it becomes difficult to attach the tubular part 11to the filter-attached portion 53. Further, in this embodiment, thethickness of the connection-end opening 13 is adjusted to be equal to orlarger than a sum of the thickness of the inner body portion 171 and thethickness of the outer body portion 173. Accordingly, when thenozzle-like filter-attached portion 53 is inserted as is shown in FIG.3, a sufficient contracting force acts on the filter-attached portion53. This prevents the ventilation member 100 from easily falling offfrom the filter-attached portion 53.

The gas permeable filter 19 fixed to the filter-end opening 15 of thetubular part 11 can be made of a material having dustproofness,waterproofness, and gas permeability. In order to merely prevent theentry of water droplets, those made of fiber materials, for example, afabric, a nonwoven fabric, a net, and a powder sintered porous body or afoam having a pore diameter of 10 μm or greater, can be used as the gaspermeable filter 19. More than one of these materials may be used incombination or in the form of multiple layers. In a case where thesurface is hydrophilic, the surface may be coated with a water-repellentand oil-repellent agent, such as an agent based on fluorine or silicon.

In a case where high waterproofness is required, it is possible to use aresin porous membrane that can be manufactured by a known drawing methodor extracting method. The pore diameter of such a porous membrane can be10 μm or smaller. The water-repellent and oil-repellent agent describedabove may be coated thereon when the necessity arises. From theviewpoint that satisfactory waterproofness is expected, the average porediameter of the porous membrane is preferably in a range of 0.01 μm to10 μm both inclusive. In this embodiment, a porous membrane made ofpolytetrafluoroethylene is used as the gas permeable filter 19. Inaddition, in this embodiment, the gas permeable filter 19 is thermallywelded to the filter-end opening 15 of the tubular part 11. However, theformer may be fixed to the latter by other means, for example, with theuse of an adhesive agent. Further, the gas permeable filter 19 simplymay be attached to the cover part 31 without being fixed to the tubularpart 11.

FIG. 7 is a perspective view of the cover part when viewed from the sidefrom which the tubular part is fit therein. FIG. 8 is a perspective viewof the cover part when viewed from the side opposite to the side of FIG.7. As shown in FIG. 7 and FIG. 8, the cover part 31 is formed of analmost circular bottom portion 35 and a tubular side wall portion 39,and as a whole, it is shaped like a cap suitable to prevent waterdroplets or the like from directly adhering to the gas permeable filter19. Protruding spacers 33 are disposed on the bottom portion 35 of thecover part 31 on the side facing the gas permeable filter 19. Thespacers 33 are disposed at plural points (three or more points) in thecircumferential direction of the circular bottom portion 35 at regularangular intervals. As shown in FIG. 1 and FIG. 3, in an attached statewhere the tubular part 11 is fit in the cover part 31, the spacers 33support the tubular part 11 along the filter-end opening 15 and therebyprevent the gas permeable filter 19 from contacting closely with thebottom portion 35 of the cover part 31. A clearance functioning as a gaspassage AR₂ thus is defined.

Plural (three or more) fixing pieces 37 for fixing the tubular part 11are provided to the side wall portion 39 of the cover part 31 at thepositions corresponding to the spacers 33 on the bottom portion 35. Thefixing pieces 37 extend linearly rearward along the inner peripheralsurface of the side wall portion 39, that is, in the direction towardwhich the cover part 31 is open. A taper TS is provided to each fixingpiece 37 for the tubular part 11 to slide into the cover part 31 withease. Because the inner edge of the fixing piece 37 is present on theouter side in the radius direction relative to the inner edge of thecorresponding spacer 33, when the tubular part 11 is pushed into thecover part 31, the tubular part 11 is allowed to move forward until itcomes into contact with the spacers 33. As is shown in FIG. 3, in theattached state where the tubular part 11 is fit in the cover part 31,the side wall portion 39 of the cover part 31 surrounds the tubular part11 in the circumferential direction. In the direction parallel to thecenter axis line O, the fixing pieces 37 of the cover part 31 fasten thetubular part 11 over a broad range across the filter-end opening 15 andthe body portion 17. Because both the inner body portion 171 and theouter body portion 173 contribute to the exertion of a contraction forceinduced by elastic deformation of the tubular part 11, the cover part 31and the tubular part 11 are assembled firmly with each other.

As with the tubular part 11, the cover part 31 as described above can bemanufactured by molding resin using a known injection molding process. Amaterial of the cover part 31 can be hard thermoplastic resin having norubber elasticity, examples of which include but not limited topolypropylene, polyethylene, polyethyleneterephthalate, and ABS. Byforming the tubular part 11 from elastomer and the cover part 31 fromhard thermoplastic resin, the tubular part 11 is allowed to undergoelastic deformation so that it is firmly fixed to the inside of thecover part 31. In addition, in this embodiment, fixing pieces are notprovided to the tubular part 11 that undergoes elastic deformation, andinstead, the fixing pieces 37 are provided to the cover part 31. In theattached state where the tubular part 11 is fit in the cover part 31,the hard fixing pieces 37 exert a strong force in the direction of thecenter axis line O on the tubular part 11. Accordingly, a strong forceis required to pull out the tubular part 11 from the cover part 31. Thiseliminates not only the need for other fixing means, such as screwclamps, but also the need for stoppers for preventing a fall-off. Inaddition, in order to secure the largest possible opening area of thefilter-end opening 15 as in the tubular part 11 adopted in theventilation member 100 of the invention, the filter-end opening 15 tendsto be thinner. When the thickness of the filter-end opening 15 becomesinsufficient, an elastic restoring force needed to fix the tubular part11 to the cover part 31 is thought to become weaker. However, such aproblem hardly occurs according to the fixing pieces 37 of thisembodiment. Further, as is shown in FIG. 3, when the nozzle-likefilter-attached portion 53 is inserted into the tubular part 11, a forceis applied to the tubular part 11 from the inside, too. Accordingly, aninconvenience, such as falling-off of the cover part 31 alone, isextremely unlikely to occur.

It goes without saying that the cover part 31 can be made of elastomerand the tubular part 11 can be made of hard resin. Also, the fixingpieces may be provided to the tubular part 11. However, the nozzle-likefilter-attached portion 53 provided, as is shown in FIG. 3, to thehousing 51 that needs ventilation is made of hard resin or metal. Hence,by forming the tubular part 11 from elastomer, it is possible to providethe ventilation member 100 that can be attached readily to thefilter-attached portion 53.

An action of the ventilation member 100 when the ventilation member 100is attached to the filter-attached portion 53 of the housing 51 of thedevice now will be described. Assume that the internal pressure of thehousing 51 is higher than the external pressure. Then, a gas (air)within the housing 51 enters into the gas passage AR₁ of the tubularpart 11 through the connection-end opening 13. The gas also spreads in aclearance between the front end face 171 a of the inner body portion 171and the gas permeable filter 19. The gas having passed through(permeated through) the gas permeable filter 19 then reaches the gaspassage AR₂ defined between the gas permeable filter 19 and the bottomportion 35 of the cover part 31. The gas having reached the gas passageAR₂ diffuses to the outside of the ventilation member 100 by way of thegas passages AR₃ defined between the respective fixing pieces 37 and theadjacent fixing pieces 37.

A ventilation member 101 adopting a tubular part 12 as shown in FIG. 4is also suitable. The ventilation member 101 includes the cover part 31same as the one described with reference to FIG. 1 and the other relateddrawings. A difference is the internal structure of the tubular part 12.

The tubular part 12 shown in FIG. 4 is common with the tubular part 11described above in that the opening area of a filter-end opening 16 ismade larger than the opening area of a connection-end opening 14. To bemore concrete, in the cross section encompassing the center axis line O(the cross section of FIG. 4), the tubular part 12 is configured to havea tapered surface inclined by a specific angle with respect to thecenter axis line O as an inner peripheral surface 18 p of a body portion18 between the connection-end opening 14 and the filter-end opening 16.When configured in this manner, the body portion 18 is of a shape whosediameter becomes larger as in the direction of the side of thefilter-end opening 16 (frontward). By tapering the inner peripheralsurface 18 p in this manner, it is possible to have different openingdiameters (opening areas) at the both ends. The tubular part 12configured in this manner is inferior to the tubular part 11 describedabove in terms of the cooling time during injection molding.Nevertheless, it has an advantage that the relatively simple shape canreduce the tooling cost.

Second Embodiment

FIG. 9 is a sectional perspective view of a second embodiment of theventilation member of the invention. FIG. 10 is a perspective view ofthe ventilation member of FIG. 9. The gas permeable filter 19, however,is omitted in FIG. 9. Applicable objects and the function of aventilation member 200 of the second embodiment are the same as those ofthe ventilation member 100 described in the first embodiment above. Theconfiguration is also common in that a gas permeation quantity per unittime is increased owing to the effective area of the gas permeablefilter 19 that is enlarged by making the opening area of a filter-endopening 65 larger than the opening area of a connection-end opening 63.A major difference from the embodiment described above is that fixingpieces 97, which play a crucial role in determining the relativepositions of a tubular part 61 and a cover part 81, are formedintegrally with the tubular part 61.

As shown in FIG. 9 and FIG. 10, the ventilation member 200 includes thetubular part 61, the gas permeable filter 19, and the cover part 81. Thetubular part 61 is formed of the connection-end opening 63, which is anopening to which a device that needs ventilation is to be connected, thefilter-end opening 65, which is an opening to which the gas permeablefilter 19 is attached, and a body portion 67 between the connection-endopening 63 and the filter-end opening 65. The interior of the bodyportion 67 defines a through-hole penetrating through from theconnection-end opening 63 to the filter-end opening 65, and thisthrough-hole forms a gas passage AR₄. As shown in FIG. 11 and FIG. 12,the body portion 67 of the tubular part 61 is of a stepped shape havinga stepped surface 61 p that is exposed to the inside of the through-hole(gas passage AR₄). The diameter of the body portion 67 starts toincrease from the stepped surface 61 p. The filter-end opening 65 havinga large opening area and the connection-end opening 63 having a smallopening area thus are formed.

As shown in FIG. 13 and FIG. 14, the cover part 81 is the same as thecover part 31 of the first embodiment above except that the fixingpieces 37 are omitted. In short, spacers 93 are disposed on a bottomportion 95 of the cover part 81. By allowing the tubular part 61 to beseated on the spacers 93, it is possible to prevent the gas permeablefilter 19 from contacting closely with the bottom portion 95. A gaspassage AR₅ thus is defined.

As shown in FIG. 9 and FIG. 10, fixing pieces 97 that play a role offixing the tubular part 61 to the cover part 81 are provided to the bodyportion 67 of the tubular part 61 in the rear of the stepped surface 61p at plural points in the circumferential direction at regular angularintervals. Each fixing piece 97 has a shape that protrudes outward inthe radius direction about the center axis line O′. A protruding amountof the fixing pieces 97 in the outer side direction is adjusted to belarger than the major diameter of the filter-end opening 65.Accordingly, in an attached state where the tubular part 61 is fit intothe cover part 81, the fixing pieces 97 are in contact with the innerperipheral surface of the side wall portion 99 of the cover part 81,which allows the fixing pieces 97 and the body portion 67 to undergoelastic deformation. Consequently, a contraction force acts on thetubular part 61 and the tubular part 61 is fixed to the inside of thecover part 81.

As is shown in FIG. 9, in the attached state where the tubular part 61is fit into the cover part 81, the gas passage AR₅ is defined betweenthe gas permeable filter 19 (not shown) and the bottom portion 95 of thecover part 81. Likewise, a gas passage AR₆ is defined between the outerperipheral surface of the tubular part 61 and the inner peripheralsurface of the cover part 81. A gas thus is allowed to circulate betweenthe gas passage AR₄ and the gas passages AR₅ and AR₆ via the gaspermeable filter 19.

For the materials of the gas permeable filter 19, the tubular part 61,and the cover part 81, reference should be made to the description forthe materials of the counterparts in the embodiment above.

Regarding the fixing pieces to fix the tubular part to the cover part,there is a case where they are provided to the cover part as in thefirst embodiment above and a case where they are provided to the tubularpart as in the second embodiment. Further, as an example of thecombination of the first example and the second example, the fixingpieces may be provided to each of the tubular part and the cover part.

Third Embodiment

FIG. 15 is an exploded perspective view of a third embodiment of theventilation member of the invention. FIG. 16 is a longitudinal crosssection of the ventilation member of FIG. 15.

As shown in FIG. 15 and FIG. 16, a ventilation member 300 includes atubular part 102, a gas permeable filter 19, and a cover part 110. Thetubular part 102 is of an almost circular cylindrical shape, and a firstgas passage BR₁ and second gas passages BR₂ isolated from the first gaspassage BR₁ are formed in the interior thereof. The first gas passageBR₁ is a gas passage that directly communicates with the interior spaceof the housing of a device. The second gas passages BR₂ are gas passagesthat directly communicate with the exterior space of the housing of thedevice and the ventilation member 300. The cover part 110 is a partinside of which the tubular part 102 is fit. It is formed of a bottomportion 112 forming a gap TH between itself and the gas permeable filter19, a side wall portion 114 extending from the bottom portion 112 tosurround the tubular part 102 from the outside, and spacers 116 thatpromote the formation of the gap TH by preventing the tubular part 102from contacting closely with the bottom portion 112. The cover part 110has a structure substantially similar to the counterparts in theembodiments described above.

The gas permeable filter 19 is attached to one end of the tubular part102 so as to close an opening 103 on the basis of the first gas passageBR₁ and openings 104 on the basis of the second gas passages BR₂. A gasis allowed to circulate between the first gas passage BR₁ and the secondgas passages BR₂ via the gap TH between the gas permeable filter 19 andthe cover part 110 as well as the gas permeable filter 19. Whenconfigured in this manner, the gas headed in a direction from the firstgas passage BR₁ to the second gas passages BR₂ or in the oppositedirection passes through the interior of the tubular part 102 and thegas permeable filter 19 twice for each. It is thus possible to achieve aventilation member that excels more in durability against foreignmatter.

Also, as shown in the cross section of FIG. 16, the side wall portion114 of the cover part 110 and the tubular part 102 are in close contactwith each other across the entire region in the circumferentialdirection without forming any clearance. In other words, according tothe ventilation member 300 of this embodiment, only the gas circulatingin the second gas passages BR₂ is allowed to flow in and out between theinterior and the exterior of the housing of the device. When configuredin this manner, foreign matter will not enter through a clearancebetween the cover part 110 and the tubular part 102. The durabilityagainst foreign matter thus is enhanced further.

To be more concrete, the tubular part 102 includes an inner portion 106in which the first gas passage BR₁ is formed, and an outer portion 108that defines the second gas passages BR₂ between itself and the innerportion 106. The inner portion 106 is a portion to which the housing ofthe device is to be connected directly, and the outer portion 108 is aportion that is to directly contact closely with the side wall portion114 of the cover part 110. These inner portion 106 and outer portion 108are disposed concentrically, and the end face of the inner portion 106and the end face of the outer portion 108 are flush with each other onthe side on which the gas permeable filter 19 is attached. The opening103 on the basis of the first gas passage BR₁ and the openings 104 onthe basis of the second gas passages BR₂ are closed by the common gaspermeable filter 19. In other words, not only the gap TH between the gaspermeable filter 19 and the cover part 110 and the first gas passage BR₁are partitioned by the gas permeable filter 19, but also the gap TH andthe second gas passages BR₂ are partitioned by the gas permeable filter19. When configured in this manner, should a part of the gas permeablefilter 19 be damaged, the function of the ventilation member 300 is notlost as long as either one of the regional portion closing the first gaspassage BR₁ and the regional portion closing the second gas passages BR₂remains intact. The ventilation member 300 thus may be used continuouslywithout causing a problem.

In addition, coupling portions 109, which are formed integrally with theinner portion 106 and the outer portion 108, are provided between theseportions at plural points in the circumferential direction. The pluralsecond gas passages BR₂ are formed between adjacent members of theadjacent coupling portions 109. The coupling portions 109 formed in thismanner are able to secure the second gas passages BR₂ between the innerportion 106 and the outer portion 108 with ease. The coupling portions109 can be made of the same elastomer as the one forming the innerportion 106 and the outer portion 108. When the tubular part 102 is fitinside the cover part 110, the coupling portions 109 undergo elasticdeformation. The side wall portion 114 of the cover part 110 and thetubular part 102 thus are in close contact with each other across theentire region in the circumferential direction without forming anyclearance. Hence, not only is it possible to firmly fix the tubular part102 to the inside of the cover part 110, but it is also possible toattach the ventilation member 300 to the filter-attached portion 53 ofthe housing 51 (see FIG. 3) in a reliable manner. Further, it ispreferable to locate the spacers 116 of the cover part 110 at positionscorresponding to the positions of the coupling portions 109, that is, tobring the intervals of the spacers 116 to be disposed into agreementwith the intervals of the coupling portion 109 to be disposed. Whenconfigured in this manner, it is possible to prevent the second gaspassages BR₂ from being closed by the spaces 116.

Also, in this embodiment, only the single first gas passage BR₁ isformed so as to encompass the axis line O of the tubular part 102, andthe second gas passages BR₂ are formed at plural points (five points) atequiangular intervals so as to surround the first gas passage BR₁. Thenumber of the second gas passages BR₂ to be formed can be adjusted bytaking the assembled strength between the tubular part 102 and the coverpart 110 into account, and they can be formed, for example, at 2 to 15points (preferably, 3 to 8 points). Also, in order to ensure thesufficient assembled strength between the tubular part 102 and the coverpart 110 and to save space at the same time, the thickness of the innerportion 106 and the thickness of the outer portion 108 with respect tothe radius direction are, for example, in a range of 0.5 mm to 1.0 mmboth inclusive, respectively.

Also, assuming that the thickness direction of the gas permeable filter19 is the axis line direction, the side in the axis line direction onwhich the gas permeable filter 19 is located is the front side, and theside on which the housing of the device is supposed to be located is therear side, then the rear end portion 106 t of the inner portion 106protrudes rearward more than the rear end portion 108 t of the outerportion 108. When configured in this manner, when the ventilation member300 is attached to the housing of the device, it is possible to secure asuitable distance between the housing and the outer portion 108 of thetubular part 102. Consequently, it is possible to prevent the occurrenceof water droplets or oil droplets adhering to the surface of the housingbridge the housing and the outer portion 108 of the tubular part 102through the action of surface tension, thereby allowing the waterdroplets or oil droplets to close or enter into the second gas passagesBR₂. By adjusting a protruding quantity h of the rear end portion 106 tof the inner portion 106 to fall within a range, for example, of 0.5 mmto 2 mm both inclusive, it is possible to achieve the advantagesdescribed above in a satisfactory manner without the need tosubstantially change the dimensions of the overall ventilation member300.

Regarding the area of the opening 103 on the basis of the first gaspassage BR₁ and the area of the openings 104 on the basis of the secondgas passages BR₂, the one that should be larger the other is notparticularly limited, and any of patters (1) through (3) as follows canbe adopted:

(1) the area of the opening 103 on the basis of the first gas passageBR₁ is made larger than the area (a total of areas) of the openings 104on the basis of the second gas passages BR₂;

(2) the area of the opening 103 on the basis of the first gas passageBR₁ is made smaller than the area (a total of areas) of the openings 104on the basis of the second gas passages BR₂; and

(3) the both areas are made equal.

To be more concrete, the area of the opening 103 on the basis of thefirst gas passage BR₁ can be in a range of 20 mm² to 130 mm² bothinclusive (preferably, in a range of 30 mm² to 60 mm² both inclusive),and the area of the openings 104 on the basis of the second gas passagesBR₂ can be in a range of 5 mm² to 140 mm² both inclusive (preferably, ina range of 5 mm² to 60 mm² both inclusive). It should be noted, however,that because the both gas passages BR₁ and BR₂ are closed by the gaspermeable filter 19 in this embodiment, when the area of the opening onthe basis of one of the gas passages is made too large in comparisonwith the area of the opening on the basis of the other gas passage,there is a concern that the gas permeation resistance increases.Accordingly, it is preferable to adjust the area S3 of the opening 103on the basis of the first gas passage BR₁ and the area S4 of theopenings 104 on the basis of the second gas passages BR₂ so that theratio (S3/S4) thereof is 0.3 or greater (preferably, 0.8 or greater),and the absolute value of a difference of the areas of these openings,|S3−S4|, is 120 mm² or smaller (preferably, 30 mm² or smaller, and morepreferably, 0).

Although it is not shown in the cross section of FIG. 16, when a crosssection encompassing the axis line O that passes through the center ofthe tubular part 102 is observed, it is preferable to configured in sucha manner that the outer peripheral surface of the tubular part 102 andthe inner peripheral surface of the side wall portion 114 of the coverpart 110 are tapered surfaces slightly inclined with respect to the axisline O. When configured in this manner, not only is it possible toincrease the assembled strength between the tubular part 102 and thecover part 110, but it is also possible to increase the assembledstrength between the filter-attached portion 53 of the housing 51 (seeFIG. 3) and the ventilation member 300. More preferably, the anglebetween the outer peripheral surface of the tubular part 102 (or theinner peripheral surface of the side wall portion 114 of the cover part110) appearing on the cross section and the axis line O is adjusted tofall within a range of 2° to 15° both inclusive (more preferably, in arange of 3° to 10° both inclusive).

Alternatively, as with a ventilation member 300′ shown in FIG. 17, itmay be configured in such a manner that only the opening 103 on thebasis of the first gas passage BR₁ is closed by the gas permeable filter19 and the openings 104 on the basis of the second gas passages BR₂ arenot closed by the gas permeable filter 19. When configured in thismanner, the second gas passages BR₂ directly communicate with the gap THbetween the gas permeable filter 19 and the bottom portion 112 of thecover part 110 without through the gas permeable filter 19. In otherwords, a gas headed from the interior to the exterior of the housing orin the opposite direction passes through the gas permeable filter 19only once, which can reduce the gas permeation resistance. The gaspermeation capability can be therefore enhanced. Alternatively, it maybe configured in such a manner that only at least one of the pluralsecond gas passages BR₂ is closed by the gas permeable filter 19 whilethe rest are not closed as in the example shown in FIG. 17.

In addition, tubular parts described below may be adopted instead of thetubular part 102 described with reference to FIG. 15 through FIG. 17.

A tubular part 120 shown in FIG. 18 has the second gas passages BR₂whose shape is improved. To be more specific, in this tubular part 120,an opening 125 on the basis of the first gas passage BR₁ and openings126 on the basis of the second gas passages BR₂ are of a common circularshape. The configuration is common with the tubular part described abovein that the first gas passage BR₁ is formed in the inner portion 121 andthe second gas passages BR₂ are formed between the inner portion 121 andthe outer portion 122.

A tubular part 130 shown in FIG. 19 has an outer portion 132 thatprotrudes frontward more than an inner portion 131. Also, couplingportions 138 interposed between the inner portion 131 and the outerportion 132 are almost flush with the outer portion 132 at a level inthe axis line direction. The gas permeable filter 19 can be attached tothe inner portion 131 so as to close only an opening 135 on the basis ofthe first gas passage BR₁. Openings 136 on the basis of the second gaspassages BR₂ are not closed by the gas permeable filter 19 and arethereby exposed frontward in the axis line direction. In other words,the coupling portions 138 are used also as spacers that form a gapbetween the cover part 110 and the gas permeable filter 19. Whenconfigured in this manner, the spacers 116 in the cover part 110 can beomitted.

The tubular part 130 has a ring-like rib 137 protruding outward in theradius direction on the outer peripheral surface of the outer portion132. By allowing the rib 137 to be positioned between the tubular part130 and the side wall portion 114 of the cover part 110, it is possibleto increase the assembled strength between the tubular part 130 and thecover part 110. It goes without saying that the rib 137 can be providedto the tubular part 102 shown in FIG. 15 and the tubular part 120 shownin FIG. 18. Alternatively, such a rib may be provided on the innerperipheral surface of the side wall portion of the cover part 110. Therib 137 may be provided in a single line. However, from the viewpoint ofpreventing the entry of foreign matter into a clearance between thetubular part 130 and the cover part 110, it is preferable to provide theribs 137 in plural lines from top to bottom in the axis line directionas with the tubular part 130 of FIG. 19.

A tubular part 140 shown in FIG. 20 has an inner portion 141 thatprotrudes frontward more than an outer portion 142. The gas permeablefilter 19 can be attached to the inner portion 141 so as to close onlyan opening 145 on the basis of the first gas passage BR₁. By configuringin such a manner that openings 146 on the basis of the second gaspassages BR₂ are not closed by the gas permeability filter 19, it ispossible to achieve high gas permeation capability. Also, ribs 147 canincrease the assembled strength between the tubular part 140 and thecover part 110.

A tubular part 150 shown in FIG. 21 has the first gas passage BR₁ andthe second gas passage BR₂, each provided at a single point. The size ofan opening 155 on the basis of the first gas passage BR₁ is the same asthose in the tubular parts described above. However, the area of anopening 156 on the basis of the second gas passage BR₂ is made slightlysmaller. Nevertheless, because the dimension of the gas permeable filter19 is adjusted so that it closes only the opening 155 on the basis ofthe first gas passage BR₁, the opening 156 on the basis of the secondgas passage BR₂ is not closed by the gas permeable filter 19.Accordingly, the tubular part 150 also achieves excellent durability andsatisfactory gas permeation capability at the same time. The tubularpart 150 also has an inner portion 151 that protrudes rearward in theaxis line direction and an outer portion 152 that defines the second gaspassage BR₂ between itself and the inner portion 151. It goes withoutsaying that a rib 157 can be provided to the tubular part 150.

The invention claimed is:
 1. A ventilation member, comprising: a tubularpart, in an interior of which a gas passage for an object that needsventilation is formed, the tubular part having a connection-end openingwhich is an opening on a side on which the object is to be connected,and a filter-end opening, and a body portion positioned between theconnection-end opening and the filter-end opening; a gas permeablefilter disposed at the filter-end opening of the tubular part to closethe filter end opening; and a cover part, inside of which the tubularpart is fit, wherein: the cover part includes a bottom portion thatfaces the gas permeable filter in an attached state where the tubularpart is fit inside from a side of the gas permeable filter and a sidewall portion that extends from the bottom portion so as to surround thefilter-end opening and the body portion from outside; gaps functioningas gas passages that communicate with an exterior are formed in theattached state between the bottom portion of the cover part and the gaspermeable filter and between the side wall portion of the cover part andthe body portion of the tubular part; a material of the cover part isthermoplastic resin having no rubber elasticity; a material of thetubular part is elastomer; the cover part comprises fixing pieces formedon an inner surface of the side wall portion for securing the tubularpart to the cover part, the fixing pieces each extending in a directiontoward an opening of the cover part; the fixing pieces push the tubularpart toward a center axis line of the tubular part in the attachedstate, so that the tubular part is allowed to undergo elasticdeformation, the center axis line being parallel to a thicknessdirection of the gas permeable filter, and the fixing pieces areconfigured to contact a side portion of a side wall of the tubular partin the attached state.
 2. The ventilation member according to claim 1,wherein the body portion of the tubular part comprises an outer surfaceand an inner surface, the fixing pieces are in contact with the outersurface of the body portion in the attached state, and the body portionis compressed in a thickness direction thereof through elasticdeformation of the body portion when the ventilation member is attachedon a nozzle-like filter-attached portion such that the inner surface ofthe body portion is in contact with the nozzle-like filter-attachedattached portion.
 3. The ventilation member according to claim 1,wherein each fixing portion is tapered so as to ease attachment of thetubular part to the cover part.
 4. The ventilation member according toclaim 1, wherein the cover part comprises plural spacers that supportthe tubular part along the filter-end opening at the attached state, andthe plural spacers prevent the bottom portion of the cover part fromcontacting closely with the ventilation filter entirely, so that one ofthe gaps formed between the bottom portion of the cover part and the gaspermeable filter is secured.
 5. The ventilation member according toclaim 1, wherein the gas permeable filter is fixed on the tubular part.6. The ventilation member according to claim 1, wherein thethermoplastic resin having no rubber elasticity is at least one selectedfrom polypropylene, polyethylene, polyethylene terephthalate and ABS,and the elastomer is based on at least one selected from polystyrene,polyolefin, polyvinyl chloride, polyester, polyurethane, polyamide andfluoropolymer.